Vacuum cleaner



G. E. LOFGREYN VACUUM CLEANER Filed 00 6, 1932 3 Sheets-Sheet INVENTOR fi/J ATTORNEY Nov. 26, 1935.

G. E. LOFGREN VACUUM CLEANER Filed 0011-. 6, 1952 5 sheetssheet 2 'INVENTOR Nov. 26, 1935.

G. E. LOFGREN v VACUUM CLEANER Filed Oct. 6, 1932 5 Sheets-Sheet 6 INVENTOR /J ATTORNEY Patented Nov. 26, 1935 PATENT; OFFICE VACUUM CLEANER .Gustaf Einar Lofgren, Rye, N. Y., assignor to Electrolux Corporation, Dover, Del., a corporation of Delaware Application October 6, 1932, Serial No. 636,500

23 Claims.

My invention relates to vacuum cleaners and particularly to vacuum cleaners having an inclosed dust bag.

One of the objects of my invention is to provide means for indicating to the operator when sufficient dust has accumulated in the bag so that it is desirable to empty the bag.

A further object of my invention is to utilize the pressure difference on the two sides of a dust bag, that is the pressure drop through the dust bag due to clogging the pores by dust, to indicate the condition of the dust bag and to accomplish this by simple and reliable mechanism. In this connection, in the preferred embodiment of my invention, I combine features of extended surface for dust deposit with dust indication, a single member serving to permit a large dust bag and move the dust bag and through movement of the dust bag register its condition.

Further objects of my invention will be apparent from the following description thereof considered in connection with the accompanying drawings which form a part of this specification and of which:

Fig. 1 is a side view, partially in crossvsection, of a vacuum cleaner unit embodying my invention in a preferred form;

Fig. 2 is a view, partially in cross-section, taken on the line 2-2 of Fig. 1;

Fig. 3 is a top view of a modified indicating device which may be used in connection with the cleaner unit shown in Fig. 1;

Fig. 4 is a cross-sectional view, taken on the line 4-4 of Fig. 3;

Fig. 5 is a cross-sectional view of another form of my invention;

Fig. 6 is a cross-sectional view, taken on the line 66 of Fig. 7, of an indicating device shown in Fig. 5;

7 is a top view of the device shown in 1g- Fig. 8 is a cross-sectional view taken on the line 88 of Fig. 6; and

Figs. 9 through 13 are cross-sectional views of five further embodiments of my invention.

Fig. 1 shows a vacuum cleaner unit including an air-tight casing comprising a barrel l0, pref.-

erably cylindrical in form, and made of sheet metal or other suitable stiff impervious material. Secured to one end of barrel I is a ring ll provided with an inwardly extending flange l2. Secured to the other end of the barrel is a ring l3. The outlet end of the barrel is closed by means of a cover member I4 which is securedto ring l3 by means of suit-able snap fasteners l5, which may be similar in all respects to the snap fasteners shown in Fig. 2. Cover member I4 is provided with a, threaded outlet opening IS.

A motor I! is suitably supported adjacent to the outlet end of the casing and is providedwith an armature shaft l8 upon which is mounted a centrifugal fan I 9 comprising one or more rotors.

A fan housing 20 is suitably supported by the motor I! or the casing and surrounds the rotors of the centrifugal fan l9. The housing is pro- 1 vided with an intermediate wall 2| between the two rotors and a forward wall 22 in front of the first rotor. These walls are provided with central apertures 23 and 24, respectively, the latter opening being guarded by a perforated plate 25.

A ring 26 which forms part of a dust separator and which is provided with an outwardly extending flange 21 which carries a rubber packing member 28 is adapted to seat against flange l2 of ring ll. Ring 26 is held in place by means of an end member 29 forming part of the casing which seats against the packing 28 and is held in position by means of hook fasteners l5, as is shown in Fig. 2. A coupling member 30 is adapted to screw into a threaded inlet opening 3| formed in member 29. Coupling is provided with a central aperture 32 which is adapted to receive the hose leading from a cleaning implement or the like. Coupling 3 is adapted to fit the threaded outlet opening l6 when it is desired 30 to use the vacuum cleaner as a blower. A dust bag 5| of flexible material, which is pervious to air but prevents the passage therethrough of dust particles, is suitably secured to and supported by ring 26.

A cage 33 having open work wall structure,

I preferably made of heavy wire, suitably reenforced so as to be rigid, is slidably supported on rounded projections 34 within the smooth bore of barrel l0 between fan housing 20 and the inlet end of the casing. The cage hasan open front end supported by a ring 35 having two outwardly extending projections 36 diametrically opposite each other. The rear end of the cage is closed by an open work wall to which is secured a memher 31 which in turn is secured to one end of a coil spring 38. The other end of spring 38 is encased or supported in a member 39 of electrical insulating material such as rubber and is adapted to. abut against perforated plate 25. Within the front end of barrel In there is secured on either side thereof, a stop 40 (Fig. 2) which engages the projections 36 on ring 35 and prevents the cage from being moved beyond this point by spring 38. One of the stops 40 is pro 56 vided with a forked extension 4| between the prongs of which one of the projections 36 is adapted to slide. The cage is thus prevented from rotating within barrel II].

An aperture 42 is formed in the upper side of barrel l0. Aperture 42 is made air-tight by means of a piece of glass or other transparent material 43 held in place by a flanged member 44. Located on the upper side of, and fixedly secured to, cage 33 and between the cage and barrel In, so as to be visible through opening 42, is a plate constituting a signal 45. Plate 45 carries some designating symbol to indicate they position of cage 33 with respect to the casing. As shown in Fig. 2, the right hand portion of the plate may be of one color, such as white, while the left hand portion of the plate may be of a different colorysuch as red. The lines 46 indicate the color red. If desired, words may be printed or otherwise impressed on the plate to indicate the position of the cage.

The cleaner as a whole is supported'on a pair of runners 4'! secured atone end to ring H and at the other end to ring l3. These runners permit the cleaner to slide easily over a supporting surface. A handle 46 is provided for carrying the cleaner. An electric switch 49 controls the supply of current to the motor I! while electric contacts 50 are adapted to engage a plug for supplying current to the motor.

What is shown on the drawing may be termed the cleaner unit. To the cleaner unit is attached the hose which conducts air to or away from the unit and by means of which the unit is drawn on the carpet or floor.

The operation is as follows:

Upon rotation of fan l9 by motor H a current of air is caused to flow through the air-tight casing from the inlet 3| thereof to the outlet I6. If a hose leading from a cleaning implement is connected to opening 32 in coupling 30, and the implement is passed over a surface to be cleaned, dust-laden air will be drawn into the interior of dust bag 5|. Here the dust is deposited while the air passes through the pervious dust bag and through perforated plate 25 and opening 24 to the fan. The fan discharges the air through and. around motor l1, thereby cooling the motor, and the air is finally discharged through outlet IS. The bar 5| offers a resistance to the flow of air therethrough. This resistance causes a higher pressure to exist within the bag than in the space within the casing outside of the bag but ahead of fan IS. The result is that there is a tendency for the bag to be inflated. This causes the closed end of the bag to press against the end of cage 33, which in turn tends to slide cage 33 toward the fanhousing. Spring 38 is provided to resist this tendency up too. certain point. As dust continues to accumulate in the bag, the resistance to air flow therethrough is increased and hence the forceexerted by the bag against the end of cage 33 is increased. When the value of this force (the differential of pressure inside and outside the bag) reaches a certain point, which corresponds to a quantity of dust in the bag such that the latter should be cleaned, the cage will have moved an appreciable distance to the right, as viewed in Figs. 1 and 2 against the increasing resistance of spring 38. Inasmuch as signal 45 is secured to the cage it likewise moves to the right and the red por-' tion 46 becomes visible through opening 42. The operator then knows that the bag has accumu lated suflicient dirt so that, for eflicient operation of the machine, the bag should be emptied.

Inasmuch as an ordinary spring has a resistance which varies in direct proportion to the amount which the spring is compressed or expanded, it will be seen that the movement of the free end of the spring has a direct relation to the pressure drop through the dust bag. The signal may be considered as indicating the compression of the spring which is thus a measure of the extent of clogging of the dust bag.

In order to clean the bag it is only necessary to remove member 29 by unfastening catches l5 whereupon the bag may be lifted out of the cage and the casing.

In this embodiment the cage 33 and the resisting spring have a dual function in that as well as being a primary indicator member responsive to the pressure drop through the dust bag for indicating the extent of clogging of the dust bag, they also serve to permit a larger bag, and hence one having greater surface, than the length of the dust bag space provided by the cage and the casing and longer than would be the space provided for the dust bag if the cage were omitted. The bag thus can fold in the cage and for this purpose I preferably provide atapered bag of a diameter everywhere less than the diameter of the cage. Also, movement of the cage tends to clear parts of the dust bag surface of dust. The cage and tapered extended dust bag are disclosed and claimed in a copending application Serial No. 636,499 filed by me concurrently herewith to which reference may be had for additional description.

In Figs. 3 and 4 I have illustrated a different form of dust indicator. Ring 35 of cage 33 is provided with an additional projection 52 at the top thereof, which may be similar to projections 36 described in connection with Figs. 1 and 2. A support 53 is secured with n barrel l0 between the inlet end thereof and the end ring 35 of the cage and carries a rack 54, the right hand end of which (as shown) is forced against projection 52 by means of a spring 55. Rack 54 is provided with teeth 56 which engage a pinion 51 mounted on a shaft 58 which is journalled at its lower end in support 53. The other end of shaft 58 extends through an opening in barrel I0 and is provided with a pointer 59 constituting the signal. Pointer 59 moves over a scale 60 which is arranged beneath a window 6|.

In operation, when the cage 33 moves to the right, due to increase of pressure drop through the bag, in turn due to an accumulation of dust in the dust bag, as was described in connection with Figs. 1 and 2, spring 55 causes rack 54 to follow the cage. This movement of the rack rotates pinion 51 and with it shaft 58 and pointer 59. When the pointer has moved in a clockwise direction (as shown) to the position shown in dash and dot lines in Fig. 3, it indicates to the operator that the dust bag should be cleaned.

In Figs. 5 to 8, I have illustrated still another form of my invention wherein 'I utilize the tendency of an inflated bag to take a cylindrical or expanded form to operate the indicating device. This embodiment differs from that shown in Figs. 1 and 2 in that the cage is omitted. The dust bag 5| is secured to ring 26 which in turn is secured to the inlet end of barrel In in the same manner as previously described. Secured to the inlet end of barrel ill at the top thereof is one end of a leaf spring 62. The other end of the spring is provided with a slot 63 through which forcing pin 66 downwardly against leaf spring 62.

. accumulation of dirt in the bag, as has been.

extends a headed pin 64 for guiding and supporting that end of the spring. The spring is formed so as to be normally bowed to such an extent that it extends intothe space-which would normally be occupied by thedust bag 6| when the latter is inflated. Indicating mechanism designated generally'by reference character 66, is secured to barrel l6 and is provided with a slidable hollow pin 66 (see particularly Fig. 6) the lower end of which bearsagainst the bowed portion of spring 62... Pin 66 slides within housing 61 of the indicating mechanism, but is prevented from rotating by means of pins 66 which engage grooves 69 in pin 66. A pin, I6 rotatably journalled in housing 61, but restrained from longitudinal movement by a collar 1|, extends within the hollow center of pin 66. A spring I2 is provided for Pin 10* is provided with a helical groove I3 which engages a. pin 14 (Fig. 8) carried by hollow pin 66. Thus, when pin 66 is moved upwardly, pin 14 working in groove 13 causes pin I to rotate in a clockwise direction, as viewed from the top w in Fig. '7. The upperend of p n I0 is provided with a pointer constituting a signal 15 which moves over a scale 16 which is visible through a window ll of the indicator.

The operation of the device shown in Figs. to 8, is as follows: i y

when the pressure difference between the space inside the bag and the space immediately outside thereof within the casing increases, due to the previously. explained, the bag exerts a greater force in attempting to become fully inflated and to take a cylindrical form or other form of maximum volume depending on the shape of the bag.

' The tension of the bowed portion of spring 62 tends to prevent the top of the bag from becoming cylindrical. As the pressure difference increases, the force exerted by the bag against the spring overcomes the tension of spring 62 and causes it to become straightened. This causes the central portion of the spring to be raised whereupon the right hand end of the spring moves to the-right, as viewed in Fig. 5.

When the central portion of the spring moves upwardly, it moves pin 66 upwardly which, in the manner previously described, causespointer or signal to move in a clockwise direction. When thesignal has moved to the end of the scale in this direction'it-indicates to the operator that the bag requires cleaning. The bag may be removed and cleaned in-the same manner as described in connection with the previous modification.

In Fig. 9 I have shown a still further embodiment of my invention. A spring I3 is secured to plate which is carried by ,fan housing 20. The other end of spring 16 is secured to a perforated plate 19. When spring 18 is expanded the distance between plate-l9 and ring 26 is less than the length of dust bag 5|, wherefore the dust bag. cannot be fully inflated with the plate in this position. As dust accumulates in 'the ba and the pressure drop therethrough increases, in

other words when the pressure within the bag with respect to that immediately outside thereof in the handle is a signal 34. The upper end of signal 34 is adapted to move in front of window 33, while the other end bears against the rear of plate 19. A spring 36 is arranged to hold the lower end of member 34 against plate 19. 5 when plate 19 is moved towards the fan housing, due to an accumulation of dirt in the bag, -member 34 is caused to pivot in a counter-clockwise direction, as viewed in Fig. 9, and the upper end thereof becomes visible through window 32. This indicates to the operator that so much dirt has accumulated within the dust bag 6| that ,the latter requires cleaning in order that the device may operate efficiently.

It will be obvious that instead of using differ- 1 flange a; is secured to barrel ill in the plarie, of

abutment 9|. A perforated plate or frame 94 is arranged to be pressed against the forward side 25" of filter 90 and to hold the filter in place between it and abutment 9| and flange 93. The filter may comprise a circular frame carrying a layer of cloth on eitherside thereof between which may' bt located filter material. It will be seen that plate 94 is normally a stationary member. A cage 33 is slidably positioned within barrel l0 and slides on rounded projections-,34. A spring 95 is suitably secured to the closed end of cage 33 and is adapted to abut against plate or frame 35 94. The inlet end of barrel i0 is provided with a ring 96, which is similar to ring ll shovh in Fig. 1 but differs therefrom in that the inwardly extending flange has an inner diameter equal to the inner diameter of barrel lii. This provides an opening of barrel iii which is as large as the internal diameter of anypart of the barrel and hence cage 33 may be removed from this end of the barrel. r

Dust bag 5i is supported at its open end by a ring 91, which is similar to ring 2$shown in Fig. 1, .but has a larger outwardly extending flange 98. This flange is provided with a packing 29 which I is clamped betweenring 96 and end member 29 The'open end of cage 33 abuts against flange 96 and is thus prevented from further movement towards the left as viewed in Fig. 10 when the dust bag is clamped in position. When the end of the cage is in contact with flange 96 spring 95 is slightly compressed.

Y A member 99 is slidably supported within bar.- rei ill by. means of a headed pin I00 extending through a-slot formed in the member. One end of member 99 is bent at right angles to form a 1 projection llli which is held against the closed end of cage 33 by means of a spring 102 secured to the other end of member 99 and anchored to a projection I03. on the inside of the barrel.. ,Thus, when, cage 33 moves to the right, as viewed .in

vFig. 10,.it moves member 99 along with it, and

when the cage moves to the left spring I02 causes member 99 to follow the cage.

Secured to barrel Ill is a handle 80 having a hollow end portion. 8i wprovided with an air-tight window82. :.Pivotally"mounted. within hollow portion 6] is'a signal I04 comprising a bell-crank lever pivoted at I05. One end of the lever is provided with a plate I06 which, in one of its two positions, is visible through window 32. The

other end of the lever is secured to a spring llil,

' 55 as that shown in Fig. 10, and hence a description the other end of which is secured to member 09. The pivot point I05 is so situated with respect to I01 is caused to pass through dead center when the member 99 moves from one end of its path of travel to the other. This causes the signal I04 to have snap-action. The movement of the signal is limited in one direction by a stop I08 and in the other direction by striking the interior of the handIe at I09.

When the fan I9 is rotated, it causes the passage of air throughth casing and through the 99 has passed a line drawn from the other end aosaeso direction. This causes striker H8 to-strike the edge of bell III, and the resulting sound warns the path of travel ofmember 90 that the spring. I

the operator that the bag requires cleaning. It wfll be noted that, in the position-shown in Fig. 12, striker H0 is not in contact with hell i I I, but very close to it. The flexible nature of arm H8 allows striker I II to strike the bell when the bellcrank lever is snapped but then removes the striker from contact with the bell. This is desirable, as continued contact with the hell would deaden the-sound.

In the modification shown in Fig. 13, movement of-the cage 33 towards the right, as viewed in this figure, is resisted by a plurality of springs I I9 which are secured at one end to the open end of cage 33 and are anchored at the other end to of the spring through the pivot point I05. When member 90 has been moved by the cage suificiently to carry the end of spring I01 past this line, the spring snaps the signal I04 quickly in a clockwise direction, as viewed in Fig. 10, so.that the disc I06, which may be coloredin any distinctive,

If it is desired to clean a ring I23 secured within barrel i0. Thus, when the bag 5| exerts force againstthe cage 33'it moves the cage by expandingsprings H9. In this modification the cage is shown .with a signal 45 similar to that shown in Fig. e

In Fig. 13, the bag SI is shown in its fully extendedstate-in order to clearly show the length of the bag as compared with the length of the 'space between the ring II and 'the closed end of cage 33 into which the bag is forced when the cleaner is assembled. In going into-this smaller space, the bag is folded in some such manneras or replace filter 90, this'niay be done by remov- J ins cage 33 after the bag has been removed. Inasmuch as spring 95' is secured to the case. it

J will be removed with the cage. The plate 04 may 0 then be tilted so as to avoid striking projection Il l and withdrawn from the barrel I0 and filter 00 may be. removed'in the same manner. If desired, filter 03 may be fastened to plate 04 so that the two members may be removed as a unit.

The device-shown in Fig. 11 is similar to that shown in Fig. 10, with the exception that. spring III is to cage 33 by means of a hooked member III. In this modification no filter is eniiloyeg the fan and the dust.

so bag and hence it is not 11 for the operator to remove the cage. The cage may be put inplace during the course of manufacture of the cleaner and hence tlfe spring I" may be connected'directly to it.

The op ration of this modification is the same thereof need not be repeated. In Fig. 11 the signal I04 is shown in the position in which it is visible through window 32, thereby indicating 60 that the dust bag should be cleaned.

In the embodiment shown in Fig. 12, an audible signal is employed instead of a visual one. A

thatjndicated in theother figures. Fig. 13 likewise clearly shows the taper of the dust bag. I

While this taper is not necessary, it is preferable in order toprovide increased space towards the closed end of the cage to accommodate the folds and wrinkles ofthe bag. It is preferable that tion; they will beworked towards the closed end 4 due to the fiow of air through the bag and the cordance with dust accumulation.

movement of cage 33. g

, It will be appreciated that, in the above described embodiments of my invention employ-v ing a spring or springs and a plate or cage arranged tobe moved by the bag as the latter is .being inflated, the spring or'springs and the plate or cage may-be considered ascomprising a yieldable member.

Itwlll be appreciated thatmy invention can be embodied in a great variety of forms.

What I claim is:

1. In a vacuum cleaner, n casing,a' movable signal, resilient mechanism constructed and arrangedrto move said signal in one direction, a dis- '55 tensible member pressing against said mecha n'ism to move it in opposite direction, and. airfiow means to produce a pressure difi'erential on oppositesides of said distensible member in so- 2. In a vacuum cleaner, a casing, a movable signal, resilient mechanism including a spring conbell III is suitably secured withidthe hollow end portion II of handle 30. A bell-crank lever III 5 comprisingarigidarm ll3andafiexiblearm H4 is pivoted atland is arranged to move between stops}. m and u The end pffiexible when, the cage 33 has moved a sufficient distance to the right, as viewed in Fig. 12, due toinci'ease in force exerted by the dustbag, the lower end'. of spring IOLpasses dead center and'causes the structed and arranged to move said signal in one direction on spring expansion, a distensible menipressing against said mechanism to move it in opposite direction, air-flow means to produce a pressure differential on oppodte sides of said 'distensiblemembe 75 bell-crank lever 2 to be snapped in a clockwise separating member, of an indicator including a v10 to'resist distensioncf the dust separating mernher, and a signal movable in responseto distortion of said spring.

5. A vacuum cleaner including. an air-tight casing having an air inlet and, an air outlet, means 15 to produce flow of air therethrough, a dust bag in said casing, and resilient mechanismio removably retain said dust bag in folded condition in said casing while permitting movement thereof due to variation of pressure drop through the said mechanism.

6. A vacuum cleaner including an air-tight casing having an air inlet and an air outlet, means toproduce flow of air therethrough, a dust bag in 25 said casing, and means -to removably retain said dust bag in said casing in folded condition while permitting movement thereof due to variation of pressure drop through the dust bag,and means to indicate movement of the retaining means,

through, a cage having openwork 'wall structure 'movably mounted in said casing in the path of 35 air flow therethrough, a dust bag adapted to be disposed in and held by said casing and to rest in said cage in folded condition, and means to indicate the position of said cage in said casing. 8. In a vacuum cleaner, an air-tight casing pro- 40 vided with an inlet opening and an outlet opening, means for causing flow of airtherethrough, a cage having openwork wall structure movably mounted in said casing in the path of air flow therethrough, a dust bag adapted to be disposed 45 in and held by said casing and to rest in said cage in folded condition, a spring; arranged to exert force against said cage in opposition to the direction of flow of air in said casing, and'means to indicate movement of said cage. 4

a 9. In a-vacuum cleaner, a casing having an inlet for dust-laden air and an outlet for air from which dust has been removed, means to cause flow of air through said casing, a dust bag of flexible air-pervious material in said casing so posi- 56" tioned therein that the air which enters as dustladen air passes therethrough, said dust bag being mounted in the casing so as to be distensible due to the flow of air, means to resist distention of the dust bag, the last mentioned means being mvable'.in"variable degree depending on' the pressure .drop t ough the dust bag, and means to indicate degree of movement of the resisting means,

10. In a vacuum cleaner, a casing having an inlet for dust-laden air and an outlet for air from which dust has been removed, means to cause flow I of air through said casing, a dust bag of flexible air-pervious material in said casing having one end thereof fixed against movement and so posi- 570 tionedwithin thecasing that all the air which enters asdust-laden air passes therethroughi said dust. bag being distensible due to the flow of air,

a, movable member in said casing against which the dust bagis pressed'due to pressure drop there- 7 through and which resists distension of the dust dust bag, and means to indicate the position of 7. In a vacuum cleaner, air air-tight casing bag, resilient means" m yieldably pressing said member against. the dust bag, whereby on increase in pressure drop said member is movedinone direction and on decrease in pressure? drop the resilient means moves said membenin the 5 opposite direction, and meansto indicate movement of said movable member, 11. In a vacuum cleaner having an air-tight casing, a dust bag in said casing and means for causing flow of air through said casing, apparatus 10 for indicating the condition of said bag comprising a 'member disposed in contact with the end of said bag, a spring arranged to press said member against said bag and to be cgmpressed when the bag is being inflated due to the passage of air through the casing, and a signal operable by movement of saidmember.

12. A vacuum cleaner comprising an air tight casing, a handle having a hollow portion secured to said casing; a distensible fibrous dust separating member in said casing, means for causing flow of air through said casing, yieldably movable mechanism. arranged to press'against said dust I separating member and to be moved as the'dust separating member is distended due to the passage of air through the casing, a window formed in the hollow portion of said' handle, and a signal pivoted with respect to said casing within said hollow portion,,oneend of said signal having engagement with said mechanism so as to be moved thereby and the other end being arranged so as to be visible through said window.

13. A vacuum cleanercomprising an air-tight casing, a handle having ahollow portion secured to said casing, a distensible fibrous dust separating member in said casing, means for causing flow of air through said casing, yieldably movable I mechanism arranged to press against'said dust separating member and to be moved as the dust separating member is distended due to the pas- 40 sage of air through the casing a window formed in the hollow portion of said handle, a signal pivoted with respect to said casing within said hollow portion, one end of said signal being arranged so as to be visible through said window, and a spring secured tosaid signal and to said mechanism,the pivot point being so located with respect'to the path of travel of said mechanism that said spring passes through dead center'when said mechanism moves from one end of its path of travel to the other. r 14. In a vacuum cleaner having an air-tight casing, a dust bag in said casing, and means for causing flow of air through said casing, apparatus for indicating the conditionof said bag compris- 5 ing a yieldable member between the side of said bag and said casing arranged to press against said bag and to be moved as the bag is inflated due to the passage of-' air through the casing, and a signal operable by movement of said yieldable 50 yieldable member arranged to press said cage against said bag and to be compressed as the bag is inflated due to suction, and a signal operable by movement of said yieldable' member.

16. In a vacuum cleaner, an air-tight casing having an inlet opening and an outlet opening,

' means for producing flow of air through said casing, a dust bag of air-pervious flexible material 76 said inlet, one end of said 17. In a vacuum cleaner, an air-tight casing having an inlet opening and an outlet opening, means for producing flow of air through said casing, a dust bag oi. air-pervious flexible material within said casing having one end open and the other end closed, means for securing the open end of said bag to said, casing. a yieldable meml6 ber within said casing, the length ofsa-id bag being greater than the distance between the place. where the bag is secured to the casing and said member, and a signal operable by movement or said member. I i a 18. In a vacuum cIean'er an air-tight casing having an inlet opening and an outlet opening, means for producingflow of air through said casing, a dust bag of air-pervious flexible material within said casi-ng between said means and bag being open and the other end being closed, means for securing the open end of said bag to said casing adjacent to said inlet, movable mechanism including a spring between said bag and the first mentioned means, the closed end of said bag being adapted to press against said. movable mechanism when the bag is being inflated'due to air flowtherethrough, and a visible signal operable by movement of said movable mechanism. 5 19. In a vacuum cleaner, an air-tight casing having an inlet opening and an outlet opening, a fan in said casing, a housing around said fan, means for driving said fan, a dust bag oi; air-' pervious flexible material within said'casing between said fan and said inlet, one end oi said bag being open and the other end being closed, means for securing the open end of said bag to said casing adjacent to said inlet, resilient mechanism secured to the front of saidta'n housing, the closed end of said dust bag being adapted to press against said resilient'mechanism', when the bag is being inflated due to air flow therethrouglr and asignal to indicate movementoi said mesh.

In a vacuum cleaner, an air-tight casing having an inlet opening and an outlet opening, a fan in said casingfa housing around said fan, means for driving said, fan, a dust bag of air-per- A vious flexible material within said casing 'between said Ian and said inlet, one end of said bag being open and the other end being closed, means for securing the open end of said bag to said casing adjacent'to said inlet, a spring secured to the front of said fan housing. a member attached to said spring, the closed end of 5 said bag being adapted to press against said member when the bag isbeing inflateddue to air flow therethrough, and a signal operable by movement of said member.

21. In a vacuum cleaner, an air-tight casing 10 having an inlet opening and an outlet opening, a fan in said casing, a housing around said fan, means for driving said fan, a dust bag of airpervious flexible material within said casing between said fan and said inlet, one end of said 15 bag being open and-the other end being closed, means for securing the open end of said bag to said casing adjacent to said inlet, resilient mechanism secured to the front of'said fan housing,

the length of said bag being greater than the dis 20.

tance between the .place where the bag is secured to the casing and said resilient mechanism, and a signal operable by movement of said mechanism.

22. "In a vacuum cleaner, an air-tight casing being adapted to be placed within said cage,

the length o'i'said bag being sumciently greater than the length of said cageso that the end of said bag presses against the end of the cage when the is being inflated due to air flow therethro, 1i, resilient means forresisting -movement4o- 01 said cage, and indicating means operable by movement of said cage.

23. In a vacuum cleaner having an air-tight v casing, a distensible flbrous dust separating mem her in said casing, and means for causing flow of air through said casing, apparatus for indicating the condition of said separating member comprising a yieldably movable mechanism arranged to press against said dust separating member and to be'moved as the dust separating 0:

member is distended due to the passage of air through the casing, a bell carried by said casing,

- and a, striker for said bell operable by movement of said mechanism.

GUSTAF EINAR IDFGREN. 

